The present invention relates to a broaching device for a silo comprising a rotor and at least one broaching arm connected to the rotor. The broaching arm is comprised of leaf springs stacked on top one another to form a leaf spring packet and further of brackets for holding the leaf springs together. The broaching arm extends to the wall of the silo and is curved opposite to a direction of rotation of the rotor. A holder is connected to the end of the broaching arm, and broaching tools are connected to this holder.
Such a device is known from German Patent 20 63 140. This device serves to loosen stored material in a silo, especially in the vicinity of the bottom portion of the silo, and to move the stored material toward transporting devices, such as a screw conveyor, for transporting the stored material outwardly. The transporting devices are arranged below openings provided within the bottom portion of the silo. The spring-elastic broaching arms may bend backwardly against the direction of rotation of the rotor under the load of the stored material whereby they may come to rest at the circumference of the rotor. Accordingly, the torque required for driving the rotor remains within feasible limits. From this extremely backwardly bent position, the broaching arms which are under a radial stress have the tendency to move outwardly so that with each revolution of the rotor their broaching tools connected to the free ends will dig deeper into the column of stored material in the direction toward the wall of the silo. Thus, a vault is formed within the stored material which has a constantly increasing diameter and which will collapse when the annular section of the stored material within the silo which supports the vault has been removed. The free ends of the broaching arms are thus positioned closely to the wall of the silo. The broaching arms are maintained in this position in which they are bent counter to the direction of rotation of the rotor, for example, by providing a cable between the free ends of the broaching arms and the rotor. This has the advantage that a great portion of the load which acts on the free ends of the broaching arms and the holders connected thereto may be compensated by the broaching arm as a pulling force component. Furthermore, with this arrangement a constant transport of the stored material within the silo into the commonly radially extending Openings of the bottom portion of the silo is achieved.
Since the broaching arm over its entire length is embodied as a leaf spring packet with leaf springs stacked on top one another held together by brackets, a displacement of the leaf springs relative to one another takes place due to the changing curvature. All of the leaf springs except the outermost leaf spring connected to the holder for the broaching tool are freely slidable within the holder. This outer leaf spring the bending deformation of which has the greatest value must also compensate the pulling force component of the load acting onto the broaching tool and is furthermore subjected to wear due to the movement of the stored material. Other parts of the broaching arms may also be subjected to extremely great wear, especially within the area of the brackets which are holding the leaf spring packet together. These brackets may be clamped in a known manner relative to the leaf spring packet by leg springs whereby the spring coils of the leg springs are arranged transverse to the longitudinal extension of the leaf spring packet and their legs are resting at the outer leaf springs.
It is therefore an object of the present invention to improve the broaching device of the aforementioned kind such that its operational safety is improved, and especially the service life of the broaching arms is increased.